Disconnecting everybody is possible, the blind icmp reset can reset the connection between a server and a client .. The reset is lanched from a client to a server(or inverted) if we launch the attack against one of them we have to know the local/internal IP address of our target.
To see the icmp reset working, the target (client/server) have to download something using tcp on the server/client (with a refreshing page for example)
For further information use google 
the tool:
http://www.gont.com.ar/tools/icmp-attacks/index.html
the screenshot:
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